The present invention relates to a new ball-point pen construction, and more particularly to a ball-point pen construction which ensures leak-tight interconnections between the writing tip, nose cone and ink reservoir using simple force-fit assembly techniques.
Ball-point pens have, for many years, been popular writing implements. They combine the ease of use of pencils with the permanency of ink pens, their cost is low, and they are reliable.
The basic structure of most ball-point pens includes a housing having an ink reservoir with a writing tip connected thereto. Depending on the type of pen that is to be produced, that is the selling price of the finished product, the housing may take any of a large number of forms and be made of many different materials ranging from hard plastic to gold or platinum.
The present invention relates to the reservoir-writing tip portion of a ball-point pen. Contained within the reservoir tube is the ink supply. Ink is dispensed through a tip, normally including a rolling ball which applies the ink to paper or other material. The tip is usually in the form of a metal cylinder with a ball supported within a socket at the front end thereof. The rear end of the tip is open and must communicate with the reservoir in a leak-tight fashion. This is often accomplished using a nose piece which may be in the form of a cone. The particular type of arrangement over which the present invention is an improvement is one wherein the metal tip, nose cone, and reservoir tube are all forced-fitted together.
Many force-fitting schemes have been applied to assembling a leak-tight connection between the elements in a ball-point pen. Most prior devices suffer from premature failure due to leaking around the interconnection joints, or are expensive to machine and assemble.
For example, U.S. Pat. No. 3,100,477 to Ermel shows, in FIG. 4, a basic force-fit type of construction representative of the prior art devices. In Ermel, the writing tip and nose cone are combined as a single unit with the nose cone force-fitted into a reduced end portion of the ink reservoir. U.S. Pat. No. 4,077,807 to Kramer et al shows a variant of the Ermel tip wherein the rear portion of the nose cone has an increased diameter to fit into the ink reservoir. This makes it unnecessary to machine the front end of the reservoir to the narrower cross section as required by Ermel. Canadian Pat. No. 506,205 to Andrews; and Austrian Pat. No. 260,724, are two further examples of prior art showing the basic force-fit construction of Ermel or Kramer et al.
A slightly stronger connection between the writing tip/nose cone arrangement and the ink reservoir was accomplished by variations on the simple force-fit structure, as shown, for example, in U.S. Pat. No. 4,077,726 to Hechtle; Swedish Pat. No. 164,128 to Clausen; and French Pat. No. 1,157,099. The various devices shown in these patents use inter-engaging ledges or other structural features requiring special machining and assembly techniques.
These force-fitted constructions, while having the major advantages of economy, simplicity of design and ease of assembly, nonetheless suffered from the major disadvantage of leakage at the connection of the elements. Accordingly, other techniques have also been applied in an endeavor to form a leak-tight seal between the writing tip and the reservoir, including a heat sealing technique wherein an ink reservoir tube is inserted into the rear of a plastic nose tip and then heat sealed around the rim; and a technique wherein the various elements are threaded so that they can be screwed together, or example as shown in French Pat. No. 57,397.
The present invention has an object to provide a ball-point pen structure wherein the writing tip, nose cone and ink reservoir can be simply and inexpensively assembled, without the need for expensive machine techniques for producing the pen elements, to produce a leak-tight construction.